Method for depositing a group IV semiconductor and related semiconductor device structures

ABSTRACT

A method for depositing a Group IV semiconductor is disclosed. The method may include, providing a substrate within a reaction chamber and heating the substrate to a deposition temperature. The methods may further include, exposing the substrate to at least one Group IV precursor and exposing the substrate to at least one Group IIIA metalorganic dopant precursor. The methods may further include depositing a Group IV semiconductor on a surface of the substrate. Semiconductor device structures including a Group IV semiconductor deposited by the methods of the disclosure are also provided.

CROSS-REFERENCE TO RELATED PATENT APPLICATION

The present disclosure claims the benefit of U.S. Provisional Patent Application No. 62/534,621, filed on Jul. 19, 2017 and entitled “A METHOD FOR DEPOSITING A GROUP IV SEMICONDUCTOR AND RELATED SEMICONDUCTOR DEVICE STRUCTURES,” which is incorporated herein by reference.

FIELD OF INVENTION

The present disclosure generally relates to methods for depositing a Group IV semiconductor and related semiconductor device structures. The present disclosure also generally relates to methods of doping a Group IV semiconductor and doping precursors which may be utilized for p-type doping of Group IV semiconductors.

BACKGROUND OF THE DISCLOSURE

The scaling of semiconductor device structures, such as, for example, complementary metal-oxide-semiconductor (CMOS) devices, has led to significant improvements in speed and density of integrated circuits. However, conventional device scaling faces immense challenges for future technology nodes.

One approach to improve semiconductor device performance is to enhance the carrier mobility and consequently the transistor drive current utilizing strain induced effects. For example, it has been shown that the hole mobility may be considerably enhanced in a p-channel silicon (Si) transistor employing stressor regions, such as, stressor regions employed in the source and drain regions of the transistor structure.

The contact resistance to the active regions of a semiconductor device structure may be a concern for on-going device improvement at future technology nodes. For example, for CMOS device structures, the contact resistance may include the electrical resistance between the contact structure and one or more stressor regions comprising the source and drain regions of the transistor structure. In the case of an n-type MOS device, the stressor region may comprise a highly doped region, i.e., with a carrier density of approximately 5×10²⁰ cm⁻³, doped with either phosphorus or arsenic. The high doping levels that may be achieved in the n-type MOS device stressor region may result in a contact resistivity as low as 0.3 mΩ-cm. However, for the p-type MOS device, the current state of the art has focused on the use of boron p-type doping utilizing a boron dopant precursor, such as, diborane (B₂H₆). The use of diborane (B₂H₆) in p-type MOS becomes prohibitive for pure Ge layers and/or as the Ge fraction is increased in Si_(1-x)Ge_(x) stressors. Efforts to increase the p-type carrier density in p-type MOS devices by the addition of further boron may result in a decline in the crystal quality of the doped stressor region and may not significantly contribute to the active carrier density in the p-type stressor region. Accordingly, alternative methods and precursors are desired that would enable high p-type doping densities in semiconductor materials, such as, for example, Group IV semiconductor materials.

In some applications, it may be desirable to deposit a Group IV semiconductor only in certain areas of a substrate. Typically, such a discriminating result is achieved by depositing a continuous Group IV semiconductor layer and subsequently patterning the Group IV semiconductor layer using lithography and etch steps. Such processing may be time consuming and expensive, and does not offer the precision required for many applications. A possible solution is the use of selective deposition processes whereby the Group IV semiconductor material is deposited only in the desired areas thereby eliminating the need for subsequent patterning steps. Accordingly, methods are desired that would enable not only high p-type doping densities in Group IV semiconductor materials but also enable selective deposition of such highly p-type doped Group IV semiconductor materials.

SUMMARY OF THE DISCLOSURE

In accordance with at least one embodiment of the disclosure, a method for depositing a Group IV semiconductor on a surface of a substrate is disclosed. The method may comprise: providing a substrate within a reaction chamber, heating the substrate to a deposition temperature, exposing the substrate to at least one Group IV precursor, and exposing the substrate to at least one Group IIIA metalorganic dopant precursor. The embodiments of the invention may also include semiconductor device structures which may comprise a Group IV semiconductor deposited by the methods of the disclosure.

For purposes of summarizing the invention and the advantages achieved over the prior art, certain objects and advantages of the invention have been described herein above. Of course, it is to be understood that not necessarily all such objects or advantages may be achieved in accordance with any particular embodiment of the invention. Thus, for example, those skilled in the art will recognize that the invention may be embodied or carried out in a manner that achieves or optimizes one advantage or group of advantages as taught or suggested herein without necessarily achieving other objects or advantages as may be taught or suggested herein.

All of these embodiments are intended to be within the scope of the invention herein disclosed. These and other embodiments will become readily apparent to those skilled in the art from the following detailed description of certain embodiments having reference to the attached figures, the invention not being limited to any particular embodiment(s) disclosed.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

While the specification concludes with claims particularly pointing out and distinctly claiming what are regarded as embodiments of the invention, the advantages of embodiments of the invention may be more readily ascertained from the description of certain examples of the embodiments of the invention when read in conjunction with the accompanying drawings, in which:

FIG. 1 illustrates a process flow diagram illustrating an exemplary deposition method in accordance with embodiments of the invention;

FIG. 2 illustrates another process flow diagram illustrating an exemplary selective deposition method in accordance with embodiments of the invention;

FIG. 3 illustrates a further process flow diagram illustrating an exemplary selective deposition method in accordance with embodiments of the invention; and

FIG. 4 illustrates a schematic diagram of a semiconductor device structure including a p-type doped Group IV semiconductor deposited in accordance with embodiments of the invention.

It will be appreciated that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help improve understanding of illustrated embodiments of the present disclosure.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Although certain embodiments and examples are disclosed below, it will be understood by those in the art that the invention extends beyond the specifically disclosed embodiments and/or uses of the invention and obvious modifications and equivalents thereof. Thus, it is intended that the scope of the invention disclosed should not be limited by the particular disclosed embodiments described below.

As used herein, the term “substrate” may refer to any underlying material or materials that may be used, or upon which, a device, a circuit or a film may be formed.

As used herein, the term “Group IV semiconductor” may refer to a semiconductor material comprising at least one of carbon (C), silicon (Si), germanium (Ge), tin (Sn), or alloys thereof.

As used herein, the term “Group IIIA metalorganic dopant precursor” may refer to dopant precursor comprising an organic compound containing a metal element, the metal element further comprising a Group IIIA metal.

As used herein, the term “monocrystalline” may refer to a material which comprises a substantial single crystal, i.e., a crystalline material which displays long range ordering. It should however be appreciated that a “monocrystalline” material may not be a perfect single crystal but may also comprise various defects, stacking faults, atomic substitutions, and the like, as long as the “monocrystalline” material exhibits long range ordering.

As used herein, the term “non-monocrystalline” may refer to a material which does not comprise a substantial single crystal, i.e., a material which displays either short range ordering or no ordering of the crystalline structure. “Non-monocrystalline” materials may comprise polycrystalline materials which may display short range ordering and amorphous materials which may display substantially no ordering of the crystalline structure.

The embodiments of the invention may include methods for depositing a Group IV semiconductor and particularly methods for depositing Group IV semiconductors comprising a Group IIIA dopant. As a non-limiting example of the embodiments of the invention, the methods may include depositing a Group IV semiconductor layer comprising a Group IIIA dopant, such as, for example, a dopant comprising one or more of aluminum (Al), gallium (Ga), or indium (In). The methods of the disclosure utilize novel Group IIIA dopant precursors, which may enable high active carrier concentrations up to, for example, active carrier concentrations of greater than approximately 1×10²⁰ cm⁻³ The methods of the disclosure may also utilize novel Group IIIA dopant precursors for achieving high active p-type carrier concentrations in Group IV semiconductors, including Group IIIA dopant precursors, such as, for example, one or more Group IIIA metalorganics. The novel Group IIIA dopant precursors described herein for achieving high active p-type carrier concentrations in Group IV semiconductors may not only provide high carrier concentrations but also retain the crystalline quality of the Group IV semiconductor. For example, Group IV semiconductors are most commonly doped with boron, utilizing diborane (B₂H₆). However, the addition of boron to a stressor region, such as, for example, to a silicon germanium stressor region, may decrease the overall strain imposed by the stressor region, resulting in a reduction in carrier mobility and consequently a reduction in semiconductor device performance. The novel Group IIIA dopants described herein also allow for a reduction in electrical contact resistance with a semiconductor device structure, such as, for example, a transistor structure.

The embodiments of the invention may also include methods for the selective deposition of Group IV semiconductor materials and particularly methods for the selective deposition of highly p-type doped Group IV semiconductor materials. Common selective deposition processes may be achieved by the addition of an etchant gas, such as hydrochloric acid (HCl), to the deposition precursors during the deposition process. However, the simultaneous co-flow of a metalorganic dopant precursor and an etchant gas during Group IV semiconductor deposition may be problematic in some embodiments. Therefore novel methods are desired which enable selective deposition of highly p-type Group IV semiconductor materials.

The methods of the disclosure may be understood with reference to FIG. 1 which illustrates a non-limiting example embodiment of a method for forming a Group IV semiconductor. For example, FIG. 1 may illustrate a method 100 for forming a Group IV semiconductor which may comprise a process block 110, wherein a substrate may be provided into a reaction chamber and the substrate may be heated to a deposition temperature within the reaction chamber. As a non-limiting example, the reaction chamber may comprise a reaction chamber of a chemical vapor deposition system. However, it is also contemplated that other reaction chambers, such as, for example, atomic layer deposition reaction chambers, and alternative chemical vapor deposition system from other manufacturers may also be utilized to perform the embodiments of the present disclosure.

In some embodiments of the invention, the substrate may comprise a planar substrate or a patterned substrate. Patterned substrates may comprise substrates that may include semiconductor device structures formed into or onto a surface of the substrate, for example, the patterned substrates may comprise partially fabricated semiconductor device structures such as transistors and memory elements. The substrate may contain monocrystalline surfaces and/or one or more secondary surfaces that may comprise a non-monocrystalline surface, such as a polycrystalline surface and an amorphous surface. Monocrystalline surfaces may comprise, for example, one or more of silicon (Si), silicon germanium (SiGe), germanium tin (GeSn), or germanium (Ge). Polycrystalline or amorphous surfaces may include dielectric materials, such as oxides, oxynitrides or nitrides, such as, for example, silicon oxides and silicon nitrides.

With continued reference to FIG. 1, the method 100 may continue by heating the substrate to a desired deposition temperature within a reaction chamber. In some embodiments of the invention, the method 100 may comprise heating the substrate to a temperature of less than approximately 700° C., or to a temperature of less than approximately 600° C., or to a temperature of less than approximately 500° C., or to a temperature of less than approximately 400° C., or even to a temperature of less than approximately 300° C. For example, in some embodiments of the invention, heating the substrate to a deposition temperature may comprise heating the substrate to a temperature of between approximately 280° C. and approximately 700° C.

Once the substrate is heated to the desired deposition temperature, the method 100 may continue by exposing the substrate to one or more deposition precursors, which may comprise one or more precursors for depositing a Group IV semiconductor and may also comprise one or more precursors for doping the Group IV semiconductor with one or more p-type dopants.

Therefore, the methods of the disclosure may comprise exposing the substrate to at least one Group IV precursor, as illustrate by a process block 120 of FIG. 1. In some embodiments, exposing the substrate to at least one Group IV precursor, the precursor comprising at least one of: silane (SiH₄), disilane (Si₂H₆), trisilane (Si₃H₈), tetrasilane (Si₄H₁₀), isopentasilane (Si₅H₁₂), neopentasilane (Si₅H₁₂), dichlorosilane (DCS), germane (GeH₄), digermane (Ge₂H₆), trigermane (Ge₃H₈), germylsilane (GeH₆Si), tin tetrachloride (SnCl₄), or methylsilane (CH₃—SiH₃).

In some embodiments, a single Group IV precursor may be utilized during the deposition process, for example, a single Group IV precursor may be utilized when the Group IV semiconductor to be deposited comprises silicon (Si), or germanium (Ge). In some embodiments, two or more Group IV precursors may be utilized during the deposition process, for example, two or more Group IV precursors may be utilized when the Group IV semiconductor to be deposited comprises a Group IV semiconductor alloy, including, but not limited to, silicon germanium carbide (Si_(1-x-y)Ge_(x)C_(y)), germanium tin (Ge_(1-x)Sn_(x)), germanium silicon tin (Ge_(1-x-y)Si_(x)Sn_(y)), germanium silicon tin carbide (Ge_(1-x-y)Si_(x)Sn_(y)C_(x)), silicon tin (Si_(1-x)Sn_(x)), silicon tin carbide (Si_(1-x-y)Sn_(x)C_(y)), or silicon carbide (Si_(1-x)C_(x)).

The deposition process for depositing a Group IV semiconductor may also comprise, exposing the substrate to at least one Group IIIA metalorganic dopant precursor, as illustrated by a process block 130 of FIG. 1. For example, in some embodiments of the invention, the deposition method 100 may comprise exposing the substrate to at least one Group IV precursor while simultaneously exposing the substrate to at least one Group IIIA metalorganic dopant precursor, i.e., the Group IV precursor and the Group IIIA metalorganic dopant precursor are co-flowed into the reaction chamber and react/decompose over a surface of the substrate disposed within the reaction chamber. The co-flow of the one or more Group IV precursors and the one or more Group IIIA metalorganic dopant precursors into the reaction chamber may be utilized to enable the dopant species to be incorporated into the Group IV semiconductor as it is deposited.

In some embodiments, exposing the substrate to at least one Group IIIA metalorganic dopant precursor may comprise, selecting the at least one Group IIIA metalorganic dopant precursor to comprise at least one of a gallium dopant, an aluminum dopant or an indium dopant.

In some embodiments of the invention, selecting the at least one Group IIIA metalorganic dopant precursor to comprise a gallium dopant further comprises, selecting the Group IIIA metalorganic dopant precursor to comprise at least one of trimethylgallium (TMG) or triethylgallium (TEG).

In some embodiments of the invention, selecting the at least one Group IIIA metalorganic dopant precursor to comprise an aluminum dopant further comprises, selecting the Group IIIA metalorganic dopant precursor to comprise at least one of trimethylaluminum (TMA) or trimethylaluminum (TEA).

In some embodiments of the invention, selecting the at least one Group IIIA metalorganic dopant precursor to comprise an indium dopant further comprises, selecting the Group IIIA metalorganic dopant precursor to comprise at least one of: trimethylindium (TMI), triethylindium (TEI), Di-isopropylmethylindium (DIPMeIn), or Ethyldimethylindium (EDMIn).

The selection of Group IIIA metalorganic dopant precursors comprising an organic component may be further beneficial in the deposition of Group IV semiconductors. For example, carbon incorporation into a Group IV semiconductor may provide further strain-engineering options in the Group IV semiconductor being deposited. Therefore, in some embodiments of the invention exposing the substrate to at least one Group IIIA metalorganic dopant precursor further comprises, incorporating carbon into the deposited Group IV semiconductor, the atomic percentage of carbon in the Group IV semiconductor being greater than approximately 0.5% at-%.

In some embodiments of the invention, it may be beneficial to deposit a Group IV semiconductor without incorporating substantially any carbon into the deposited semiconductor layer. However, since the metalorganic dopant precursors utilized herein comprise an organic component, i.e., a carbon containing component, it may be difficult to minimize the carbon incorporation into the deposited Group IV semiconductor. However, the methods of the disclosure may deposit select Group IV semiconductors utilizing metalorganic precursor dopants without any significant carbon incorporation into the semiconductor layer. As a non-limiting example embodiment, the method of depositing a Group IV semiconductor on a surface of the substrate may further comprise, depositing a germanium (Ge) semiconductor, the germanium (Ge) semiconductor being substantially free of carbon.

The embodiments of the invention may continue with a process block 140 of FIG. 1, wherein a Group IV semiconductor may be deposited on a surface of the substrate disposed within the reaction chamber. In some embodiments, depositing a Group IV semiconductor on the surface of the substrate comprises, depositing at least one of silicon (Si), germanium (Ge), silicon germanium (Si_(1-x)Ge_(x)), silicon germanium carbide (Si_(1-x-y)Ge_(x)C_(y)), germanium tin (Ge_(1-x)Sn_(x)), germanium silicon tin (Ge_(1-x-y)Si_(x)Sn_(y)), germanium silicon tin carbide (Ge_(1-x-y)Si_(x)Sn_(y)C_(x)), silicon tin (Si_(1-x)Sn_(x)), silicon tin carbide (Si_(1-x-y)Sn_(x)C_(y)), or silicon carbide (Si_(1-x)C_(x)).

The methods of the disclosure allow the Group IV semiconductor to be deposited with a high concentration of p-type dopants without reducing the crystalline quality of the Group IV semiconductor. For example, in some embodiment, depositing a Group IV semiconductor on the surface of the substrate further comprises depositing the Group IV semiconductor with a doping concentration of greater than approximately 1×10²⁰ carriers per cubic centimeter, or greater than approximately 2.5×10²⁰ carriers per cubic centimeter, or even greater than approximately 5×10²⁰ carriers per cubic centimeter.

The methods of the disclosure also allow for the deposition of a Group IV semiconductor at an increased growth rate. Not to be bound by theory or mechanism, but it is believed the Group IIIA metalorganic dopant precursors utilized herein for doping a Group IV semiconductor may act to catalyze substrate surface reactions resulting in an increased deposition rate of the Group IV semiconductor. Therefore, in some embodiments of the invention, depositing a Group IV semiconductor on a surface of the substrate further comprises, depositing a Group IV semiconductor on a surface of the substrate at a deposition rate of between approximately 10% and approximately 30% greater than the deposition rate achieved by prior art methods for depositing a p-type doped Group IV semiconductor.

The embodiments of the invention may also include methods for selectively depositing Group IV semiconductors and particularly methods for selectively depositing Group IV semiconductors which are doped p-type with at least one Group IIIA metalorganic dopant precursor. A non-limiting example method for selectively depositing a p-type Group IV semiconductor is illustrated with reference to FIG. 2, which illustrates an exemplary selective deposition method 200. The method 200 may begin at a process block 210, wherein a substrate may be provided into a reaction chamber and heated to a deposition temperature. The reaction chamber may be similar or the same as those previously described in this disclosure. In some embodiments of the invention the substrate may be heated to deposition temperature, i.e., a selective deposition temperature, of between approximately 280° C. and approximately 700° C.

The method 200 may proceed with a process block 220, wherein the method comprises exposing the substrate to at least one group IV precursor and an etchant gas. In some embodiments, the one or more group IV precursors may comprise: silane (SiH₄), disilane (Si₂H₆), trisilane (Si₃H₈), tetrasilane (Si₄H₁₀), isopentasilane (Si₅H₁₂), neopentasilane (Si₅H₁₂), dichlorosilane (DCS), germane (GeH₄), digermane (Ge₂H₆), trigermane (Ge₃H₈), germylsilane (GeH₆Si), tin tetrachloride (SnCl₄), or methylsilane (CH₃—SiH₃). The process block 220 may also comprise exposing the substrate to an etchant gas and may further comprise selecting the etchant gas to comprise at least one of chlorine (Cl₂) or hydrochloric acid (HCl). In some embodiments of the invention, the one or more group IV precursors and the etchant gas are introduced into the reaction chamber simultaneously, i.e., the selective deposition process comprises the co-flow of the one or more group IV precursors and the etchant gas into the reaction chamber such that the substrate is exposed to the one or more Group IV precursors and the etchant gas simultaneously.

The method 200 may continue with a process block 230, wherein the method comprises, selectively depositing a Group IV semiconductor on a surface of the substrate. In more detail, the embodiments of the invention may allow for the selective deposition of the Group IV semiconductor on select areas of the substrate surface. In some embodiments of the invention, the surface of the substrate may comprise one or more regions that are monocrystalline and one or more regions that are non-monocrystalline, i.e., polycrystalline or amorphous. The embodiments of the invention provide methods for selectively depositing the Group IV semiconductor on a monocrystalline surface of the substrate without any, or substantially any, deposition occurring on a non-monocrystalline surface of the substrate. Therefore the embodiments of the invention may selectively deposit Group IV semiconductor on monocrystalline surfaces of the substrate without substantially any Group IV semiconductor deposition on the amorphous and polycrystalline surfaces of the substrate. In some embodiments of the invention, the monocrystalline surfaces may comprise one or more surfaces of: silicon germanium carbide (Si_(1-x-y)Ge_(x)C_(y)), germanium tin (Ge_(1-x)Sn_(x)), germanium silicon tin (Ge_(1-x-y)Si_(x)Sn_(y)), germanium silicon tin carbide (Ge_(1-x-y)Si_(x)Sn_(y)C_(x)), silicon tin (Si_(1-x)Sn_(x)), silicon tin carbide (Si_(1-x-y)Sn_(x)C_(y)), or silicon carbide (Si_(1-x)C_(x)). In some embodiments of the invention, the non-monocrystalline surfaces may comprise one or more surfaces of a silicon oxide, a silicon nitride, or a silicon oxynitride.

In some embodiments of the invention, selectively depositing a Group IV semiconductor on the monocrystalline surface of the substrate further comprises selectively depositing an undoped Group IV semiconductor on the monocrystalline surface of the substrate. The inventors have found that the simultaneous flow of the one or more Group IV precursors and the at least one Group IIIA metalorganic dopant precursor may result in semiconductor material with low doping concentrations. Therefore, the methods of the disclosure may separate the flow of the one or more Group IV precursors from the at least one Group IIIA metalorganic dopant precursor such that Group IV semiconductors with improved p-type doping concentration may be deposited. This process may be variably referred to as cyclic δ-doping and/or cyclic atomic layer doping. Since the one or more Group IV precursors (along with the etchant gas) are utilized to selectively deposit the Group IV semiconductor, without the flow of the at least one Group IIIA metalorganic dopant precursor, the Group IV semiconductor may be selectively deposited undoped. It should be noted herein that the term “undoped” may also refer to “unintentionally doped” as the as-deposited Group IV semiconductor may comprise impurities and/or defects which may result in unintentional doping of the Group IV semiconductor. In some embodiments of the invention, selectively depositing the undoped Group IV semiconductor on the monocrystalline surface of the semiconductor further comprises depositing the undoped Group IV semiconductor to a thickness of between approximately 10 Angstroms and approximately 25 Angstroms.

The method 200 may continue with a process block 240, wherein the method comprises, exposing the Group IV semiconductor to at least one Group IIIA metalorganic dopant precursor. In more detail, as the Group IV semiconductor is initially deposited in an undoped state, the methods of the disclosure provide a means for incorporating p-type dopants into the as-deposited undoped Group IV semiconductor. Therefore, in some embodiments of the invention, exposing the undoped Group IV semiconductor to at least one Group IIIA metalorganic dopant precursors further comprises exposing the Group IV semiconductor to the at least one Group IIIA metalorganic dopant precursor until an exposed surface of the Group IV semiconductor is saturated with the at least one Group IIIA metalorganic dopant precursor.

In some embodiments of the invention, exposing the Group IV semiconductor to the at least one Group IIIA metalorganic dopant precursors may be performed at elevated substrate temperature. For example, once the surface of the Group IV semiconductor is saturated with Group IIIA dopant precursor, an elevated substrate temperature may be required to diffuse and/or redistributed the p-type dopants throughout the thickness of the Group IV semiconductor to provide the desired doping concentration and doping profile. Therefore, in some embodiments of the invention, exposing the Group IV semiconductor to the at least one Group IIIA metalorganic dopant precursor further comprises heating the substrate to a temperature of less than approximately 700° C., or to a temperature of less than approximately 600° C., or to a temperature of less than approximately 500° C., or to a temperature of less than approximately 400° C., or even to a temperature of less than approximately 300° C. For example, in some embodiments of the invention, exposing the Group IV semiconductor to the at least one Group IIIA metalorganic dopant precursor further comprises heating the substrate to a temperature of between approximately 280° C. and approximately 700° C.

Once the Group IV semiconductor material has been exposed, at elevated substrate temperature, to the Group IIIA metalorganic dopant precursor the Group IV semiconductor material may be doped p-type. For example, in some embodiment, the Group IV semiconductor may have a doping concentration of greater than approximately 1×10²⁰ carriers per cubic centimeter, or greater than approximately 2.5×10²⁰ carriers per cubic centimeter, or even greater than approximately 5×10²⁰ carriers per cubic centimeter.

The method 200 may proceed with a process block 250, wherein a decision gate determines if the method 200 continues or exits. The decision gate of process block 250 is determined based on the thickness of the Group IV semiconductor deposited, for example, if the thickness of the Group IV semiconductor is insufficient for the desired device structure then the method 200 may return to the process block 220 and the processes of exposing the substrate to at least one group IV precursor and an etchant gas, selectively depositing a Group IV semiconductor on a surface of the substrate, and exposing the Group IV semiconductor to at least one Group IIIA metalorganic dopant precursor may be repeated one or more times. In other words, the embodiments of the invention may comprise selectively depositing a Group IV semiconductor and subsequently exposing the Group IV semiconductor to at least one Group IIIA metalorganic precursor, wherein the selective deposition of Group IV semiconductor and the subsequent exposure of the Group IV semiconductor to at least one Group IIIA metalorganic dopant precursor are repeated one or more times.

Once the Group IV semiconductor has been deposited to the desired thickness the process may exit via a process block 260 and the substrate may be removed from the reaction chamber for additional device fabrication processes. However, in some embodiments of the invention, prior to removing the substrate from the reaction chamber, the substrate may be subjected to a post-growth annealing process to possibly further activate the p-type dopants and/or redistribute the p-type dopants throughout the thickness of the Group IV semiconductor. In some embodiments, the post growth anneal of the Group IV semiconductor may comprise heating the substrate to a temperature between approximately 600° C. and approximately 700° C.

The embodiments of the invention may also include additional methods for selectively depositing Group IV semiconductors and particularly methods for selectively depositing Group IV semiconductor which are doped p-type with at least one Group IIIA metalorganic dopant precursor. A non-limiting example method for selectively depositing a p-type Group IV semiconductor is illustrated with reference to FIG. 3, which illustrates selective deposition method 300. The method 300 may begin at a process block 310, wherein a substrate may be provided into a reaction chamber and heated to a deposition temperature. The reaction chamber may be similar or the same as those previously described in this disclosure. In some embodiments of the invention the substrate may be heated to deposition temperature, i.e., a selective deposition temperature, of between approximately 280° C. and approximately 700° C.

The method 300 may continue with a process block 320, wherein the substrate is exposed to at least one Group IV precursor and at least one Group IIIA metalorganic dopant precursor. The at least one Group IV precursor and the at least one Group IIIA metalorganic dopant precursor may comprise those precursors previously described herein. In some embodiments, the at least one Group IV precursor and the at least one Group IIIA metalorganic dopant precursor may be simultaneously introduced into the reaction chamber; in other words, the at least one Group IV precursor and the at least one Group IIIA metalorganic dopant precursor may be co-flowed into the reaction chamber.

The method 300 may continue with a process block 330, wherein embodiments of the invention comprise, depositing a Group IV semiconductor on a surface of the substrate. It should be noted that although the overall method 300 may comprise a selective Group IV semiconductor deposition process the individual process block 330, comprising depositing a Group IV semiconductor on a surface of the substrate, does not comprise a selective deposition process. Therefore, in some embodiments of the invention, depositing a Group IV semiconductor on the surface of the substrate further comprises, depositing a monocrystalline Group IV semiconductor on one or more monocrystalline surfaces of the substrate and depositing a non-monocrystalline Group IV semiconductor on one or more non-monocrystalline surfaces of the substrate. In other words, epitaxial growth of a Group IV semiconductor occurs on the monocrystalline surfaces of the semiconductor while non-epitaxial growth of a Group IV semiconductor occurs on the non-monocrystalline surfaces of the semiconductor, i.e., on the amorphous and polycrystalline regions of the substrate. In some embodiments of the invention, depositing the Group IV semiconductor on one or more crystalline surfaces of the substrate further comprises, depositing the monocrystalline Group IV semiconductor to a thickness of between approximately 20 Angstroms and approximately 100 Angstroms.

The method 300 may continue with a process block 340, wherein embodiments of the invention comprise, exposing the Group IV semiconductor to an etchant gas. For example, both the monocrystalline Group IV semiconductor and the non-monocrystalline Group IV semiconductor deposited in the previous process block 330 may be exposed to an etchant gas. In some embodiments of the invention, exposing the Group IV semiconductor to an etchant gas may further comprise selecting the etchant gas to comprise at least one of chlorine (Cl₂) or hydrochloric acid (HCl).

Exposure of the Group IV semiconductor to an etchant gas may be utilized to selectively remove a portion of the Group IV semiconductor from the surface of the substrate. In some embodiments of the invention, the etch rate of the monocrystalline Group IV semiconductor may be different from the etch rate of the non-monocrystalline Group IV semiconductor and in further embodiments the etch rate of the non-monocrystalline Group IV semiconductor may be greater than the etch rate of the monocrystalline Group IV semiconductor. Therefore, in some embodiments, exposing the monocrystalline Group IV semiconductor and the non-monocrystalline Group IV semiconductor to an etchant gas may further comprise substantially removing the non-monocrystalline Group IV semiconductor and simultaneously partially removing the monocrystalline Group IV semiconductor. In other words, the methods of the disclosure may allow for the selective removal of substantially all the non-monocrystalline Group IV semiconductor while retaining a portion of the monocrystalline Group IV semiconductor. In some embodiments of the invention, the time period for the exposure of the substrate to the etchant gas may be such that only the non-monocrystalline, i.e., non-epitaxial, Group IV semiconductor is removed while maintaining the majority of the monocrystalline, i.e., epitaxial, Group IV semiconductor.

The method 300 may proceed with a process block 350, wherein a decision gate determines if the exemplary method 300 continues or exits. The decision gate of the process block 350 is determined based on the thickness of the monocrystalline Group IV semiconductor deposited, for example, if the thickness of the monocrystalline Group IV semiconductor is insufficient for the desired device structure then the method 300 may return to the process block 320 and the processes of exposing the substrate to at least one Group IV precursor and at least one Group IIIA metalorganic dopant precursor, depositing a Group IV semiconductor on a surface of the substrate, and exposing the Group IV semiconductor to an etchant may be repeated one or more times. In other words, the process of depositing a Group IV semiconductor on a surface of the substrate and exposing the monocrystalline Group IV semiconductor and the non-monocrystalline Group IV semiconductor to the etchant gas is repeated one or more times. Due to the difference between the etch rate of the monocrystalline Group IV semiconductor and the non-monocrystalline Group IV semiconductor the method 300 results in a net monocrystalline Group IV deposition per cycle, wherein a cycle comprises a deposition process and a subsequent etch process. This type of process may be referred to as epitaxial cyclic deposition-etch.

Once the monocrystalline Group IV semiconductor has been deposited to the desired thickness the process may exit via a process block 360 and the substrate may be removed from the reaction chamber for additional device fabrication processes. However, in some embodiments of the invention, prior to removing the substrate from the reaction chamber, the substrate may be subjected to a post-growth annealing process to possibly further activate the p-type dopants and/or redistribute the p-type dopants throughout the thickness of the Group IV semiconductor. In some embodiments, the post growth anneal of the Group IV semiconductor may comprise heating the substrate to a temperature between approximately 600° C. and approximately 700° C.

The embodiments of the invention may also provide semiconductor device structures comprising a Group IV semiconductor deposited by the methods described herein. For example, FIG. 4 illustrates a non-limiting example of a semiconductor device structure 400, wherein the semiconductor device structure 400 comprises a double gate MOSFET, commonly referred to as a FinFET. The semiconductor device structure 400 may comprise a substrate 402, which may comprise a bulk silicon (Si) substrate. The substrate 402 may be doped either with p-type dopants (for NMOS type FinFET devices) or with n-type dopants (for PMOS type FinFET devices). In the non-limiting example semiconductor device structure of FIG. 4, the substrate 402 may comprise n-type dopants and the semiconductor device structure 400 may comprise a PMOS FinFET.

The semiconductor device structure 400 may also comprise isolation regions 404, which may comprise shallow trench isolation (STI) regions. The semiconductor device structure 400 may also comprise a Fin structure 406 extending over the top surfaces of the isolation regions 404. A gate dielectric may be disposed over the sidewalls of the Fin structure 406 (not shown) and the gate dielectric may comprise a silicon oxide or a high-k dielectric material. A gate electrode 408 may be disposed on the gate dielectric for providing electrical contact to the channel region within the Fin structure 406. The semiconductor device structure 400 may also comprise gate spacers 410 which are disposed on the sidewalls of the gate electrode 408.

In some embodiments of the invention, the semiconductor device structure 400 may further comprise p-type Group IV semiconductor stressor regions 412A and 412B deposited over the source and drain regions of the FinFET device. It should be noted that the p-type stressor regions 412A and 412B may comprise a number of facets that may result due to the difference in growth rates on the different facets of the Fin structure 406. In non-limiting example embodiments of the invention, the p-type stressor regions 412A and 412B may be deposited utilizing the embodiments of the invention described herein. For example, the p-type stressor regions 412A and 412B may comprise silicon germanium (Si_(1-x)Ge_(x)) wherein the germanium composition in the silicon germanium stressor regions may be greater than approximately x>0.2, or greater than approximately x>0.5, or greater than approximately x>0.8, or even x=1. In addition, the p-type stressor regions 412A and 412B may be doped according to the embodiments of the current disclosure and therefore the p-type stressor regions 412A and 412B may comprise a p-type doping concentration of greater than approximately 1×10²⁰ carriers per cubic centimeter, or greater than approximately 2.5×10²⁰ carriers per cubic centimeter, or even greater than approximately 5×10²⁰ carriers per cubic centimeter.

In some embodiments of the invention, an electrical contact may be made to the p-type Group IV semiconductor stressor regions 412A and 412B deposited over the source and drain regions of the FinFET device illustrated in FIG. 4. In some embodiments, the electrical contact (not shown) may comprise a silicide, such as, for example, a titanium silicide (TiSi₂). The embodiments of the invention allow for a high concentration of active p-type carriers in the source and drain stressor regions 412A and 412B which in turn may result in a reduction in the electrical contact resistance to the stressor regions. For example, the methods of the disclosure may comprise forming an electrical contact to the p-type stressor regions 412A and 412B, wherein the electrical contact has an electrical resistivity of less than 1×10⁻⁸ Ohm·cm², or less than 5×10⁻⁹ Ohm·cm², or even less than 1×10⁻⁹ Ohm·cm².

It should be noted that a non-limiting example embodiment given herein relates to p-type stressor regions formed over the source and drain regions of a FinFET device. However, the embodiments of the invention may be utilized for other purposes, for example, the p-type Group IV semiconductors deposited by the embodiments of the invention may be utilized to induce stress in other areas of a device structure, for example, by depositing a p-type stressor region over the channel region of a transistor to thereby induce strain directly in the channel region of the transistor device structure.

The example embodiments of the invention described above do not limit the scope of the invention, since these embodiments are merely examples of the embodiments of the invention, which is defined by the appended claims and their legal equivalents. Any equivalent embodiments are intended to be within the scope of this invention. Indeed, various modifications of the disclosure, in addition to those shown and described herein, such as alternative useful combination of the elements described, may become apparent to those skilled in the art from the description. Such modifications and embodiments are also intended to fall within the scope of the appended claims. 

What is claimed is:
 1. A method of depositing a Group IV semiconductor on a surface of a substrate comprising: providing a substrate within a reaction chamber; heating the substrate to a deposition temperature; exposing the substrate to a Group IV precursor and an etchant gas to form an undoped germanium semiconductor layer, wherein the substrate is exposed to the at least one Group IV precursor and the etchant gas simultaneously and wherein the Group IV precursor consists of a single Group IV precursor selected from the group consisting of: germane (GeH₄), digermane (Ge₂H₆), and trigermane (Ge₃H₈); after forming the undoped germanium semiconductor layer by completing the exposing the substrate step, exposing the undoped germanium semiconductor layer to at least one Group IIIA metalorganic dopant precursor selected from the group consisting of: triethylindium (TEI), Di-isopropylmethylindium (DIPMeIn), Ethyldimethylindium (EDMIn), trimethylaluminum (TMA), triethylaluminum (TEA), trimethylgallium (TMG) and triethylgallium (TEG), whereby flow of the at least one Group IV precursor and at least one Group IIIA metalorganic dopant precursor are separated; and redistributing p-type dopants from the at least one Group IIIA metalorganic dopant precursor throughout the undoped germanium semiconductor layer, thereby forming a doped germanium semiconductor layer.
 2. The method of claim 1, wherein depositing the undoped germanium semiconductor layer on the surface of the substrate further comprises, selectively depositing the undoped germanium semiconductor layer on a monocrystalline surface of the substrate and subsequently exposing the undoped germanium semiconductor layer to the at least one Group IIIA metalorganic dopant precursor.
 3. The method of claim 2, wherein exposing the undoped germanium semiconductor layer to the at least one Group IIIA metalorganic dopant precursor further comprises exposing the undoped germanium semiconductor layer to the at least one Group IIIA metalorganic dopant precursor until an exposed surface of the undoped germanium semiconductor layer is saturated with the at least one Group IIIA metalorganic dopant precursor.
 4. The method of claim 2, wherein exposing the undoped germanium semiconductor layer to the at least one Group IIIA metalorganic dopant precursor further comprises heating the substrate to a temperature of between approximately 280° C. and approximately 700° C.
 5. The method of claim 2, wherein selectively depositing an undoped germanium semiconductor layer and subsequently exposing the undoped germanium semiconductor layer to the at least one Group IIIA metalorganic dopant precursor is repeated one or more times.
 6. The method of claim 2, wherein selectively depositing the undoped germanium semiconductor layer on the monocrystalline surface of the semiconductor further comprises depositing the undoped germanium semiconductor to a thickness of between approximately 10 Angstroms and approximately 25 Angstroms.
 7. The method of claim 1, further comprising selecting the etchant gas to comprise chlorine (Cl₂).
 8. The method of claim 1, wherein depositing the undoped germanium semiconductor layer on the surface of the substrate further comprises: depositing a monocrystalline germanium semiconductor on one or more monocrystalline surfaces of the substrate.
 9. The method of claim 1, wherein heating the substrate to a deposition temperature further comprises heating the substrate to a temperature between approximately 280° C. and approximately 700° C.
 10. The method of claim 1, wherein forming a doped germanium semiconductor layer comprises depositing the Group IV semiconductor with a doping concentration of greater than approximately 1×10²⁰ carriers per cubic centimeter.
 11. The method of claim 1, wherein exposing the substrate to at least one Group IIIA metalorganic dopant precursor further comprises incorporating carbon into the deposited germanium semiconductor layer, the atomic percentage of carbon in the Group IV semiconductor being greater than approximately 0.5 at-%.
 12. A semiconductor device structure comprising the germanium semiconductor deposited according to the method of claim
 1. 13. The semiconductor device structure of claim 12, wherein the germanium semiconductor comprises a p-type stressor region.
 14. The semiconductor device structure of claim 13, further comprising forming an electrical contact to the p-type stressor region, wherein the electrical contact has an electrical resistivity of less than 1×10⁻⁸ Ohm·cm².
 15. The method of claim 1, further comprising heating the substrate to a temperature of between approximately 600° C. and approximately 700° C. after exposing the substrate to the at least one Group IIIA metalorganic dopant precursor.
 16. The method of claim 1, wherein the undoped germanium semiconductor layer is substantially free of carbon.
 17. A method of depositing a Group IV semiconductor on a surface of a substrate comprising: providing a substrate within a reaction chamber; heating the substrate to a deposition temperature; exposing the substrate to a single Group IV precursor and an etchant gas to form an undoped germanium semiconductor layer, wherein the substrate is exposed to the single Group IV precursor and the etchant gas simultaneously and wherein the undoped germanium semiconductor layer is formed solely by performing the exposing the substrate to the single Group IV precursor and the etchant gas and wherein the Group IV precursor consists of a single Group IV precursor selected from the group consisting of: germane (GeH₄), digermane (Ge₂H₆), and trigermane (Ge₃H₈); after forming the undoped germanium semiconductor layer by completing the exposing the substrate step, exposing the undoped germanium semiconductor layer to at least one Group IIIA metalorganic dopant precursor selected from the group consisting of: triethylindium (TEI), Di-isopropylmethylindium (DIPMeIn), Ethyldimethylindium (EDMIn), trimethylaluminum (TMA), triethylaluminum (TEA), trimethylgallium (TMG) and triethylgallium (TEG), whereby flow of the at least one Group IV precursor and at least one Group IIIA metalorganic dopant precursor are separated, redistributing p-type dopants from the at least one Group IIIA metalorganic dopant precursor throughout the undoped germanium semiconductor layer, thereby forming a doped germanium semiconductor layer. 